1. Field of the Invention
The present invention relates to the preparation of oxalyl chloride, and, more especially, to the preparation of oxalyl chloride via chloroxidation of ethylene glycol.
2. Description of the Prior Art
According to U.S. Pat. No. 2,816,140 oxalyl chloride is prepared by heating an ester of tetrachloroethylene glycol and a carboxylic acid to a temperature between 35.degree. and 135.degree. C., in the presence of a catalyst consisting of activated charcoal or certain derivatives of those elements of Group V A of the Periodic Table [Fisher Periodic Chart--1951] having atomic numbers between 7 and 33, e.g., derivatives such as the tertiary amines, amides. Also, the oxalyl chloride is formed simultaneously with trichloroacetyl chloride by the heating of tetrachloroethylene glycol bis-trichloroacetate in chlorobenzene, in the presence of dimethylformamide as the catalyst, at a temperature between 100.degree. and 120.degree. C.
Said '140 patent additionally discloses that the tetrachloroethylene glycol esters utilized in the noted reaction may be obtained by chlorination of the corresponding ethylene glycol esters, such chlorination being performed photochemically employing an excess of chlorine, at a temperature of 75.degree.-125.degree. C., typically in an inert solvent medium, such as carbon tetrachloride.
A process of the aforementioned type has the disadvantage in that it is effected in the presence of solvents [carbon tetrachloride for the chlorination of the ethylene glycol esters, and chlorobenzene for the rearrangement of the tetrachloroethylene glycol esters]; these solvents must then be separated. Further, chlorination in the presence of carbon tetrachloride [boiling point, 77.degree. C.] can be conducted only at low temperatures. Thus, a serious need remains in this art for a process which can be effected in the absence of a solvent medium, and which is susceptible to being carried out over a broad temperature range.